This application claims the benefit of the Jul. 31, 2001 priority date of German application 101 37 373.2.
The present invention generally relates to activation of circuit units to be controlled, and relates in particular to a method for driving circuit units to be controlled, in which a modified control signal is provided by means of a control signal generating device after activation via an activation unit.
In an integrated circuit (IC), a multiplicity of initialization procedures are provided after application of an external voltage. By way of example, all the internal voltages are typically generated in a generator unit and stabilized for further use in integrated circuit units to be controlled.
For operation, circuit units to be controlled, such as, for example, DRAM modules (DRAM=Dynamic Random Access Memory), require a control signal which permanently has a hold state, for example a logic one (xe2x80x9cactive highxe2x80x9d). Only after a signal defined by the hold state is present at a control input of the circuit unit to be controlled does the circuit unit process externally provided commands. A corresponding control signal having a hold state is provided for example when all the voltage generators or generator units of an integrated circuit have signaled their functionality.
In the conventional methodxe2x80x94illustrated in FIG. 4xe2x80x94for driving circuit units to be controlled a control signal 110 is fed via a connection unit 401 in parallel to a series of circuit units 202a-202n to be controlled.
In a disadvantageous manner, all the circuit units to be controlled are blocked if even just a single voltage generator of a generator unit has a malfunction, i.e. if the control signal 110 cannot be provided.
Thus, in an inexpedient manner, operation of the entire module or of the integrated circuit cannot be commenced. It is a further disadvantage that circuit units cannot be characterized in the event of a malfunction of a single voltage generator, even if they do not depend on the faulty voltage generator or the faulty circuit section in a generator unit.
Accordingly, it is extremely unfavorable that additional, cost-intensive production and characterization procedures are required for testing such modules provided with a fault in a single or a plurality of voltage generators of a generator unit.
It is thus an object of the present invention to provide a method and a circuit arrangement in which, even in the case of one or more defective voltage generators of a generator unit, integrated switching units or modules can be tested and/or operated, at least one control signal being externally predeterminable or switchable.
An essential concept of the invention consists in combining a conventional control signal in a gate unit with a hold signal that can be set externally, in order to obtain a modified control signal in this way.
One advantage of the present invention is that circuit units which are not affected by a malfunction of a voltage generator of a generator unit or the like can be tested and/or operated independently of a control signal that has possibly not been supplied by the faulty voltage generator of a generator unit (if a malfunction has occurred in one or more voltage generators of a generator unit).
An additional, cost-intensive production and characterization process is advantageously obviated.
The invention""s method for driving circuit units to be controlled essentially has the following steps:
a) application of a control signal to a control signal connection unit, the control signal being provided in a conventional manner by, for example, voltage generators of a generator unit;
b) application of an activation signal, provided by an activation unit, to an activation connection unit, the activation signal being externally predeterminable;
c) generation of a hold signal in a manner dependent on the activation signal, provided by the activation unit, by means of a switching device, the switching device being switchable either by means of a positive edge or a negative edge;
d) combination of the control signal applied to the control signal connection unit with the hold signal, generated by the switching device, by means of a gate unit in such a way that a modified control signal is obtained; and
e) outputting of the modified control signal via an output connection unit, in order to activate circuit units to be controlled even in the event of a malfunction of one of more voltage generators of a generator unit.
The subclaims contain advantageous developments and improvements of the respective subject matter of the invention.
In accordance with one preferred development of the present invention, the control signal applied to the control signal connection unit is provided by a generator unit comprising voltage generators for supplying circuit units of the integrated module with supply voltages. In an advantageous manner, the control signal indicates whether or not a corresponding voltage of a voltage generator of a generator unit is present, whereas for operation of further circuit units to be controlled or for the testing of the circuit units to be controlled, this voltage is not required if the modified control signal is generated according to the invention.
In accordance with a further preferred development of the present invention, the activation signal is applied to the activation connection unit by means of a measuring tip encased in the activation unit, thereby achieving a simple switch-on of the modified control signal into a hold state.
In accordance with yet another preferred development of the present invention, the switching device assumes a permanent hold state in response to a change in a voltage level at its input, which hold state is advantageously reset only after a turn-off of all the supply voltages for the integrated circuit.
In accordance with yet another preferred development of the present invention, an OR combination of the control signal fed via the control signal connection unit with the hold signal generated by the switching device is performed in the gate unit in order to obtain the modified control signal in an advantageous manner by means of an OR function.
In accordance with yet another preferred development of the present invention, the modified control signal provided at the output connection of the gate unit is made available to further circuit units to be controlled, thereby advantageously enabling operation of the further circuit units to be controlled.
In accordance with yet another preferred development of the present invention, the activation unit applies a positive voltage pulse to the activation connection unit, thereby effecting setting of the switching device into a permanent hold state.
In accordance with yet another preferred development of the present invention, the activation unit applies a negative voltage pulse to the activation connection unit, thereby effecting resetting of the switching device from the permanent hold state into a basic state.
In accordance with yet another preferred development of the present invention, a ground potential is provided via the activation unit to the activation connection unit, thereby effecting resetting of the switching device from the permanent hold state into a basic state.
In accordance with yet another preferred development of the present invention, resetting of the switching device is effected by a switch-off of the entire signal generating device or of the entire integrated circuit.
In accordance with yet another preferred development of the present invention, the permanent hold state of the hold signal constitutes a logic one or xe2x80x9cactive highxe2x80x9d.
The invention""s control signal generating device for providing a modified control signal furthermore has:
a) an activation connection unit for the application of an activation signal provided by an activation unit, for example a measuring tip;
b) a control signal connection unit for the application of a control signal which is provided by external circuit units;
c) a switching device for generating a hold signal in a manner dependent on the activation signal provided by the activation unit;
d) a gate unit for combining the control signal applied to the control signal connection unit with the hold signal generated by the switching device, in order to obtain a modified control signal; and
e) an output connection unit for outputting the modified control signal for further processing in circuit units to be controlled.
Exemplary embodiments of the invention are illustrated in the drawings and are explained in more detail in the description below.